1. Technical Field
The subject of this invention is firstly an electrical insulator disk for supporting a linear conductor that extends through a hole in the disk, and secondly an electrical assembly that includes such a disk.
2. Description of the Related Art
Disks of this kind are used mainly in medium and high voltage switchgear, for supporting the conductors of cables in gas-insulated switchgear or metalclad substation equipment.
There are many publications that describe as many designs for such disks. The present invention is able to improve on the disks that are described in patent publication WO2006/7037914 of the present Applicant. That disk is made of a thermoplastic polymer, and more precisely polyethylene terephthalate (PET); it is substantially flat. As can be seen below, although the present invention is manifestly applicable to disks of that kind, it can also be applied to other forms of disks, and to disks of other materials.
The disks used in the above-mentioned switchgear are subjected to severe conditions, in particular strong electric fields and high temperatures, because the current is passed in an atmosphere that is often corrosive, for which reason a special gas such as sulfur hexafluoride (SF6) is conventionally present so as to give an insulating environment around the conductor. The disks are thus liable to deteriorate over time, and are subjected to severe mechanical forces and deformations, all aggravated by working at high temperature, and to distortion due to thermal expansion, especially when assembled together with other materials. These problems are more acute with a thermoplastic material such as PET, that expands more than the thermosetting polymers that are used much more widely for such disks.